If it is hard for you to get up ledges with the super strength crate then try this method. Carry the crate go to a wall and instead of throwing the crate cancel the power. the crate should be on top of spongebob ,then press the jump button. spongebob should jump higher than normal and if he does not then move a little bit and try again.

After catching every dirty bubble once, no matter if you see it twice, walk to Squidwards house, go inside, talk to him, and open up his refridgerator. Inside you will find a map leading you to Sandy's Treedome. Now you could use the map, or just read this.

Walk to Spondebob's house, go right until you see a path telling you to go up. After going up, there will be another path telling you to go right, follow that path. On that path you will see 3 different paths. Go down the one on the left. Follow that path without going on any different ones. Then you will be at Sandy's treedome.